Ratchet operating mechanism



Dec. 22, 1953 J. B. TUCKER RATCHET OPERATING MECHANISM Filed 001;. 27, '1950 w u mm Mm un r m m w M .mm 5 7 u:

Patented Dec. 22, 1953 RATCHET OPERATING John B. Tucker, Marbleheatl,"Mass., assignorto General Electric Company, a corporation of New York Application Octoben27, 195.0,.Serial No. 192,523

"9'Clairns. 1

My invention relates to ratchet operating mechanisms and, more particularly, to arrangements for engaging and limiting the movement of the ratchet element of suchmechanisms.

,Many control devices employ .ratchets which areactuated progressively by theengagcment of some moving element with the ratchet. It is usually desirable to advance the ratchetonly one tooth at a time so that, for example, the mechanism to be controlled will .be operated after .a predetermined number of .actuations .of the ratchet. Such an arrangement necessitates that the ratchet actuating mechanism move the ratchet only the distance of one tooth duringeach cycle, and, that in returning to re-engage and advance the ratchet, it then engage the .next adjacent tooth. By my invention, I have incorporated in a single member portionsorelements for engaging the ratchet to prevent reverse movement thereof, for insuring that the ratchet ad-. vancing element in reverse movement moves backwardly only one tooth, and for providing a stop to limit the advance or forward movement of the ratchet advancing element to a distance equal to one tooth.

It is an object of my invention to provide an improved arrangement for actuating a ratchet and for positively limiting the amount of movement for each actuation thereof.

It is another object of my invention to 1 1 vide animprovedstructurefor use with a ratchet, which structure acts as a stop for theratchet, limits the forward movement of a ratchet advancing element to a predetermined amount and insures engagement of the ratchet advancing element with a particular tooth f the ratchet.

Eurther objects and advantages of my invention wi l become ap a en s t e ollowin d scription proceeds and the features of novelty which characterize my invention willbe pointed out with particularity in the claims annexed thereto and forming part of this specification.

In carrying out the objects of my invention, a flat metal strip is stamped to provide an inclined tongue for engaging a ratchet to prevent rotation thereof. A ratchet advancing member extends through the opening resulting from the bending of the tongue from the plane of the strip and engages the ratchet. rhe edge of the opening provides a stop for limiting the movement of the ratchet advancing member in a forward direction, and the tongue prevents the ratchet-engaging mechanism, during any over travel in a reverse direction, from engaging any tooth other than the next adjacent rearward tooth.

,IFora better understanding of my invention, referencemayibe had to the accompanying drawing in which Fig. '1 ,is ,a schematic representation showing anembodiment of my invention; and Fig. 2,15 an isometric view of aportion of the mechanism of Fig. 1,.

It will be apparent as the following description proceeds that themechanism of my inventionmay be employed in many devices. For example, it may readily be incorporated in a refrigerator control wherein defrosting is initiated after a pred termined number of actuations of the .ratchet. l ior purposes of illustration, however, I have indicated only the essential elements of the structure and have shown a force-applying element only in general form. Referring now to the drawing, there is ,showna control mechanism including an arm 7| pivoted fora movement aboutapini. "Thearm ji is viased'in a clockwise direction by spring 3 and 'is moved against the bias of thisspring 3 by aiorce-applying element 8. -In practice, the force-applying element 4 may, for example, be the ordinary bellows of a conventional refrigerator control which expands and contracts with changes in temperature to move the arm I.

it maybe desirable to cause some particular operation to occur after a predetermined number of cycles of the force-applying element i; for example, it may be desirable to cause defrosting of the evaporator of a refrigerator after the de-' termined number of cycles of operation. To cause such a periodic operation, suitable mechanism may be actuated by .a ratchet which is moved once during each cycle of movement of the force-applying element t. In'the form illustrated, this ratchet is shown as a ratchet wheel "5 mounted on vashaft 6. "The ratchet wheel '5 in.- cludes a plurality of teeth 7 adapted to be engaged for effecting movement of the ratchet Wheel. Themov'ement of the ratchetwheel 5 in a clockwise direction is effected by a ratchetadyancing or rotating member '8. The member 8 is in the form of a bent resilient strip which is secured to the'arm "I by rivets 9 or other suitable fastening devices. In order to permit the member to be1made of lighter material so that it will have a low spring constant in the vertical direction and can ride easily over "-tne teeth of the ratchet wheel, a stiffener It is also mounted on the arm I "by the rivets 9 and includes a curved portion 1'! engaging the member 8. This stiffener biases the member 8 in a direction toward the arm that is, in a direction to the left in the drawing- Tlh member 8 includes an upwardly extending portion [2 at the free end thereof for engaging the teeth 1 of the ratchet wheel 5. It can be seen that as the portion 12 of the member 8 is moved toward the left during the retracting or leftward moving portion of the cycle of the force-applying element 4, the ratchet wheel is moved in a clockwise direction, as indicated by the arrow. The movement of the force-applying element 4 and, hence, of the arm I, is at least equal to an amount necessary to result in the advancing of the ratchet wheel 5 by one tooth.

Regardless of variations in the amount of travel of the force-applying element 4 above the predetermined amount referred to above, it is desirable to insure that the ratchet wheel 5 is advanced only by the amount of one tooth and further to insure that the member 8 in movement toward the right, which may be regarded as its reverse movement as opposed to its advancing movement in rotating the ratchet wheel 5, can result in the portion l2 engaging only the next rearward tooth. I have provided for incorporation in a single stop member elements for accomplishing these purposes and also for engaging the ratchet wheel 5 to prevent a reverse rotation thereof. The stop member I3 is formed from a flat metal strip I4 mounted on a stationary member I5. A first portion or tongue I6 is lanced from the body of the strip 14 and is bent upwardly into a position inclined with respect to the plane of the strip l4 and also inclined with respect to the direction of movement of the ratchet-advancing or rotating member 8 and its ratchet engaging portion l2. The stop member i3 is positioned relative to the ratchet wheel 5 so that the end I! of the tongue or pawl l6 engages at all times one of the teeth 1 of the ratchet wheel 5 to prevent reverse, or counterclockwise, rotation of the ratchet wheel 5. The upwardly extending portion R2 of the ratchet-advancing member 8 passes through the opening 18 resulting from the bending of the pawl [6 out of the plane of this strip M. The left hand edge 19 of the opening it provides an element or stop portion for engaging the upwardly extending portion I2 of the resilient ratchet-advancing member 8 to limit the movement of this member and its ratchet-engaging portion IE to the left. Because of the stop provided by the edge l9, the leftward movement of the ratchet-engaging portion I2 is positively limited, regardless of the amount of retraction of the force-applying memher 4 so that the ratchet wheel is advanced only one tooth by the leftward movement of the ratchet-advancing member 8. As indicated previously, the ratchet-advancing member 8 is formed of a resilient strip so that, even though the arm I may move a greater distance to the left, the portion 2% of the ratchet-advancing member 8 moves away from the arm 1 and the upwardly extending portion 12 remains in engagement with the edge H) in the position shown. Since the upwardly extending portion 12 of the member 8 passes through the opening IS, the side edges of this strip prevent sidewise movement of the portion i2 and, hence, prevent it from slipping axially from the ratchet wheel.

Even though the leftward movement of the upwardly extending ratchet-engaging portion I2 is limited because of its engagement with the stop provided by the edge IQ of the opening l8, it would still be possible for the ratchet wheel 5 to be advanced more than one tooth, if, because of substantial overtravel of the force-applying element It and, hence, of the arm I, the ratchetengaging upwardly extending portion I2 were to move to the right by a distance equal to two or more teeth on the ratchet wheel 5. Such an occurrence, however, is also prevented by the construction of the stop member l3. Thus, the pawl 16 bent up from the plane of the strip I4 is inclined, as mentioned above, relative to the direction of movement of the ratchet-advancing memher 8. Accordingly, should the ratchet-engaging portion l2 move to the right by a greater distance than necessary to pass the tip of the tooth indicated at 2|, it rides along the surface of the pawl or tongue It: and it is impossible for the portion l2 to pass into engagement with the next rearward tooth indicated at 22. Such a condition of overtravel is illustrated by the dotted lines in Fig. l where it can be seen that the portion 12 merely rides along the surface of the inclined pawl l6 and is blocked from engagement with the tooth indicated ,at.22 or any more rearward tooth by the intervening pawl Hi. When the arm i again moves to the left, the portion l2 merely rides down along the inclined pawl l6,.engages the tooth indicated at 2!, and moves to the left until its further movement is, limited by the stop providedby the edge 19, at which time the ratchet wheel 5 has been advanced by one tooth. The stop member 13 is constructed so that the distance d between the, tip ll, of, the pawl l6 and the ratchet engaging end of theportion l2 or the edge i9 of, the opening i8. is substantially equal to the distance between. adjacent teeth of the ratchet wheel 5, therdistance d being measured between lines extending through the tip I! and the. edge 19 generally perpendicular to the toothed face [9a of the ratchet wheel 5, or more explicitly perpendicular to a line tangent to the ratchetwheel 5 in the area of engagement by the tip I? and the surface 23 of the upwardly extending portion l2. berseen that the simple construction of the stop member i3 provides a positive arrangement whereby the ratchet-engaging portion l2, in moving rearwardly, can come into engagement only with the next rearward tooth of the ratchet wheel and, in moving forwardly, is limited by the stop ill to a distance of movement after engagement with the tooth of the ratchet wheel which is equal to the distance between adjacent teeth of the ratchet wheel. Hence, the ratchet wheel is advanced by only one tooth during each actuation. This specific movement of the ratchet wheel 5 is achieved .despite overtravel in either direction by the arm I;

While 'I have shown and described a specific embodiment of my invention, I do not desire my invention to be limited to the particular construction shown'and described and I intend, by the appended claims, to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:.

1. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a ratchet-advancing member arranged to engage the teeth of said ratchet, and a single fixed stop member, said last-named member including a first portion for engaging a tooth of said ratchet for preventing reverse movement thereof and a second portion for being engaged by said ratchetadvancing member to limit the movement thereof in an advancing direction, said first portion being engaged by said ratchet-advancing member during movement in a reverse direction for actuating said ratchet-advancing member away from said It can ratchet, said first portion guiding said ratchetadvancing member into engagement with the same tooth engaged by said first portion during movement of said ratchet-advancing member in said advancing direction.

2. A ratchet wheel operating mechanism comprising a ratchet wheel adapted to be periodically rotated, a resilient ratchet wheel rotating member arranged to engage the teeth of said ratchet wheel, and a single fixed stop member, said stop member including a first portion for en aging a tooth of said ratchet wheel to prevent reverse rotation thereof and a second portion for being engaged by said ratchet wheel rotating member to limit the movement thereof in an advancing direction, said ratchet wheel rotating member being adapted for riding up on said first portion and away from said ratchet wheel during movement of said ratchet wheel rotating member in a reverse direction, said ratchet wheel rotating member being guided by said first portion into engagement with the same tooth engaged by said first portion during movement of said ratchet wheel rotating member in said advancing direction.

3. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a resilient ratchet-advancing member arranged to engage the teeth of said ratchet, and a single fixed stop member, said stop member including a first portion for engaging said ratchet to prevent reverse movement thereof and a second portion for being engaged by said ratchet-advancing member to limit the movement thereof in an advancing direction whereby said ratchet is advanced only one tooth during each advancing movement of said ratchet-advancing member, said ratchet-advancing member being adapted for riding upon said first portion and away from said ratchet wheel during reverse movement of said ratchet-advancing member, said ratchetadvancing member being adapted for riding down said first portion during said advancing movement of said ratchet-advancing member for insuring that said ratchet-advancing member engages the tooth engaged by said pawl.

4. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a ratchet-advancing member arranged to engage the teeth of said ratchet, and a single stop member, said stop member including a first portion for engaging said ratchet to prevent reverse movement thereof and a second portion for being engaged by said ratchetadvancing member to limit the movement thereof in an advancing direction, the distance between the ratchet engaging ends of said first portion of said stop member and said ratchet-advancing member when said ratchetadvancing member engages said second portion being substantially equal to the distance between adjacent teeth of said ratchet, said first portion being engaged by said ratchet-advancing member during reverse movement thereof for insuring that said ratchet-advancing member engages the tooth engaged by said first portion.

5. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a stop member including a fiat strip, a ratchetengaging tongue bent from said strip and providing an opening in said strip, said tongue engaging said ratchet to prevent reverse movement thereof, a ratchet-advancing member including a resilient strip having a ratchet-engaging portion extending through said opening, said firsting member.

6. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a stop member including a fiat strip, a ratchetengaging tongue bent from said stri and providing an opening in said strip, said tongue engaging said ratchet to prevent reverse movement thereof, a ratchet-advancing member including a resilient strip having a ratchet-engaging portion extending through said opening, said firstnamed strip being arranged to engage said resilient strip along the forward edge of said opening whereby said edge provides a stop for limiting forward movement of said ratchet-advancing member, the side edges of said opening being arranged to engage said ratchet-engaging portion to limit sidewise movement of said ratchet-engaging portion whereby lateral movement of said ratchet-engaging portion out of engagement with said ratchet is prevented.

7. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a stop member including a flat strip, a ratchetengaging tongue bent from said strip and providing an opening in said strip, said tongue engaging said ratchet to prevent reverse movement thereof, a ratchet-advancing member including a resilient stri having a ratchet engaging portion extending through said opening, said first-named strip being arranged to engage said resilient strip along one edge of said opening whereby said edge provides a stop for limiting forward movement of said ratchet-advancing member, the distance between the ratchet engaging ends of said tongue and said ratchetadvancing member when said ratchet-advancing member is engaged with said edge of said opening being substantially equal to the distance between adjacent teeth of said ratchet.

8. A ratchet operating mechanism comprising a ratchet adapted to be periodically advanced, a stop member including a fiat strip, a ratchetengaging tongue bent from said strip and providing an opening in said strip, said tongue engaging said ratchet to prevent reverse movement thereof, and a ratchet-advancing member including a resilient strip having a ratchetengaging portion extending through said opening, said first-named strip being arranged to engage said resilient strip along one edge of said opening whereby said edge provides a stop for limiting forward movement of said ratchetadvancing member, said tongue being inclined relative to the direction of movement of said ratchet-advancing member whereby any overtravel of said ratchet-advancing member during reverse movement results in said ratchetengaging portion thereof riding up said tongue, said tongue blocking engagement of said ratchetadvancing member with any tooth of said ratchet except the tooth engaged by said tongue.

9. A ratchet operating'mechanism comprising a ratchet adapted to be periodically advanced, a stop member including a flat strip, a ratchetengaging tongue bent from said strip and providing an opening in said strip, said tongue engaging said ratchet to prevent reverse movement thereof, a ratchet-advancing member including a resilient strip having a ratchet-engaging portion extending through said opening, said firstnamed strip being arranged to engage said reforward movement of said ratchet-advancingmember, said tongue being inclined. relativeto, the direction of movement of said ratchet advancing member whereby any overtravel of said ratchet-advancing member during rearward movement results in, said ratchet-engaging portion thereof riding up said tongue; said tongue;

locking engagement of said ratchet-advancing. 10 member with any tooth of said ratohetexcept-the;

tooth engaged by said tongue, the. distance, be;- tween lines extending through said' edge and throughtthe ratchet-engaging end of .saidtongue:

perpendicular to the toothed face of said ratchet being substantially equal to the distance between adjacent teeth of said ratchet.

JOHN B. TUCKER.

References Cited in the file of this patent UNITED STATES PATENTS,

Number Name Date 545,883 Friederich Sept. 10, 1895 656,380 Smith Aug. 21, 1900 1,112,839 Roth Oct. 6, 1914 1,403,767 Goff Jan. 17, 1922 2 ,389,695 Stenhammer Nov. 2'7, 1945 

